Statistical Mechanics and Plasma Physics is a core course in B. Sc. (Honors) Physics curriculum. The course endeavors to present the basics of Statistical Mechanics and Plasma Physics together with a number of elementary applications of these basic principles. After a discussion of the concepts of probability, the postulates of classical mechanics  are  developed  in  various  ensembles  of  physical  relevance.  The  ideas  thus  developed  for  the  classical  systems will be shown to have serious limitations when applied to quantum systems. Subsequently, we develop the correct theory  of  statistical  mechanics  for  quantum  systems  and  show  that  classical  results  can  be  recovered  from  the quantum theories in the high temperature - low density limit. Finally, the course would cover basics of plasma physics with focus on charge neutrality, plasma oscillations and the Debye length, collisions, thermal plasmas and shock waves in plasmas.